Sheet metal stretching press



April 11; 1944. P E FLOWERS SHEET METAL STRETCHING PRESS Filed Feb. 20, 1941 6 Sheets-Sheet l I uveum mun. a FLOWERS ATTORNEYS April 11, 1944.

P E. FLOWERS SHEET METAL STRETCHING PRESS Filea Feb. 20

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P. E. FLOWERS SHEET METAL STRETGHING PRESS Filed Feb.' 20, 1941 6 SheetsSheet 3 INVENTOR WERJ ATTGRNHJ PAUL FLO P. E. FLowERs SHEETMETAL STRETCHING PRESS Filed Feb. 20, 1941 6 Shets-Sheet 4 April 11, 1944. P. E. FLOWERS SHEET METAL STRETCHING PRESS 7 Filed Feb. 20, 1941 6 Sheets-Sheet 5 :IlllllllIlll I F I I I I I l ll INVENTOR PAUL E. FLOWERS,

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April 11, 1944, P. E. FLOWER-s 2,346,213

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Patented Apr. 11, 1944 sneer METAL s'ran'rcnmo mass Paul E. Flowers, Mount Gilead, Ohio, assignor to The Hydraulic Development Corp. Inc., Wilhmington, DeL, a corporation of Delaware Application February 20, 1941, Serial No. 379,875

19 Claims.

This invention relates to presses of the type that employ'mechanism for clamping the workpiece to the press. Certain types of sheet metal articles are economically fabricated by means of a stretching press in which a plain sheet of metal is bent at the proper places, and stretched in other places until the desired configuration of the article is obtained.

It is necessary to secure opposite edges of the metal sheet to the press, and during the forming operation the operator causes a platen to move upwardly by fluid pressure against the under surface of the metal sheet or strip. The shape of the article isv controlled in part by the amount of pressure exerted at the platen and also in part by the amount of slippage permitted at the jaws.

After the distance between the jaws and the amount of slippage at the jaws have been 'determined, assuming that the metal sheet has been,

placed in position, the operator by controlling the fluid pressure applied to the moving platen can determine the shape into which the metal sheet is formed. It is therefore necessary that the operator have a full view of the metal strip during the stretching operation, and no obstructions to this view should be permitted.

In the prior art form of press it is usual to provide the same amount of slippage or full clamping provide a stretching press in which adjustment can be made of the jaws as acomplete body with v the press. F

' Another object is to provide mechanism'by which the clamping device halves can bead usted' respect to theother jaw body and with respect to with respect to one another so as to obtain any desired clamping or slipping eflect at any point throughout the length of each jaw.

These two objects are carried out, in brief, by

subdividing each clamping'a'ssembly into a number of individually adjustable clamping blocks mounted on a support which can beswung in the horizontal'plane, and also moved in relation to the vertical axis of the press.

In order to provide for full gripping effect on the strip, i. e., without any slippage whatsoever,-

it has been customary to employ a two-part clamping device in which the gripping surfaces-of corrugated or grooved ina criss-cross or diagonal effects over the entire length of one or both jaws therefore over the entire width of the metal strip. Under these conditions the number of shapes which can be formed in a press of this character is limited. When articles of intricate design are to be fashioned it may be necessary to provide full clamping effects at one or more points along the edge of the strip, and different amounts of slippage at other points. On occasion, other special clamping and slipping effects must be provided in order to procure the desired stretched shape which may be a. complicated design. For example, it may be necessary to move both halves of the jaws bodily either toward or away from the central stretching axis of the press, or in the case of a long jaw, to move only one end of the jaw with respect tothe press or to move both ends of the jaw in opposite directions. In fact, the'shapes into which a metal strip can be bent and stretched are almost without number when the press is operated by a skilled workman and the Jaws are given universal movement as a body, and in addition can be adjusted as between jaw halves to allow any amount of slippage orfull clamping point orpoints throughout the line or laws.

Among the objects of the present invention is to.-

. allel paths. Thus aline or a point contact withthe strip anywhere throughout the clampingdeto move toward the device are provided with a. knife edge or its equivalent. This edge exerts a compressional force of an intense character over aline contact across the metal strip. The strains caused by these gripping forces may be sohigh, in the case I of powerful presses, as to tear the metal. The

same condition arises even when the jaws are manner, because theclamping forces are concentrated at one or more limited areas of the metal.

Consequently another objectof the present 111- vention is to provide an improved stretching press I clamping device in which the tearing effect on the metal is reduced to a minimum, even when the stretching forces and the necessary gripping effects to counteract these forces are considerable.

This object is. carried out, in brief, by providing the clamping blocks, referred to hereinbefore,

with perfectly smooth gripping surfaces, these surfaces being arranged parallel to one another and to the metal strip. Inorder to obtain flat contact with the strip over the entire gripping surface of each block, a toggle mechanism is provided that permits the blocks to move with respect to one another and with respect to the metal strip, these movementsvbei-ng constrained to parvice is avoided. The blocks are initially held lightly in contact with the strip, and the operation of the toggle mechanism is such that a pull on the metal strip will'cause the clamping blocks oneanother in parallel paths, thus to exert a. clamping eifect on the strip in proportion to the pla pull on the strip by the moving Still another object is to provide a conveniently operated structure, simple in design, for

simultaneously opening the clamping blocks inorder either to insert a metal strip or to remove the stretched piece of metal. This object is attained by mounting the blocks on a com- -mon support. This support is actuated by a suitably positioned lever in such a direction that the blocks .are caused to move about their toggle connection and thus to recede from one another and to leave a space between the jaw surfaces so as to permit the strip to be removed from the clamping device without effort. It is therefore apparent that the clamping blocks are individually adjustable with respect to one another, as pointed out in the earlier stated objects, and are adjustable as a unit in order to insert or remove a metal strip from the clamping device.

A still further object is to provide a stretching press in which the mechanism employed for making a preliminary adjustment of the position of the jaws can be temporarily removed from the press, so as not to interfere with the operators view of the metal strip during the stretching operation. In carrying out this object I em- 90 degrees so as to lie alongthe length of the press, and in accordance with another feature of my invention two additional hydraulically operated rains are provided to accommodate a different position of the strip. When these rams are not in use their cylinders can be swung out of position so as not to interfere with the operation of the machine on a strip laid transverse of the press.

The invention will be better-understood when reference is made to the following specification and the accompanying drawings.

In the drawings:

Figure 1 is a layout of the hydraulic system showing the pumps, platen, 'jaws and cylinders in diagrammatic form.

Figure 2 is a side elevation of the improved press with a portion to the left of the platen broken away. It will be noted that the platen ploy a hand wheel device which operates from sprockets and chains in such a way as to provide a universal horizontal movement of each line of clamping assemblies, and after the posiu .fied form of the press, in which the platen is positioned lengthwise of the press instead of Another object is to provide a stretching press Q employing two sets of clamping devices which can be moved hydraulically either toward or away from the metal strip, and, at any rate of speed. For this purpose I employ hydraulically these cylinders being controlled by a, suitably positioned valve.

In the case of relatively large stretching presses it is usual to provide hydraulically operated rams at each end. of the platen rather than a single ram at the middle of the platen. However, when the end rams are employed there is a tendency for the rams to move at unequal speed, even though the same pressure fluid is admitted to the cylinders. Again, in the case of an article having a complicated shape, it may be desirable to move-one end of the platen at a faster rate than the other end, in which casediiferent fluid pressure are applied to the end rams of the transversely thereof.

Figure 8 is a sectional view of the clamping jaws taken along the line 8-4 in Figure 6.

Figure 9 is a section taken between the jaws along the line 99 in Figure 8.

Figure 10 is an enlarged sectional view of'the jaws taken along the line IO- lll in Figure 6. Figure 10 shows the left-hand pair of jaws in elevation more fully to illustrate the toggle connection between the jaws.

Figure 11 is a sectional view taken along the line lI-ll in Figure 5.

Referring more particularly to Figure 2, the

. frame of the machine is constituted of long fiat stresses brought about solely by reason of this diiference in movement.

Another object ofthe invention is to equalize these stresses regardless of the difference in rate of speed at which the rams are'either accidentally or deliberately operated. This object is attained, in brief, by arranging the rams in such a way as to permit them to swing in the horizontal direction so 'as to assume positions in which the resultant stresses are reduced to a minimum.

otherwlseremovably secured to a platen 6 carried at each end on rams 1, which are adapted to reciprocate in a pair of cylinders 8. The rams 1 preferably terminate at the top in a hemispherical bearing cap 9 which flts within a suitably shaped opening in the platen.

The cylinders 8 are hung on the trunnioned bearings l0 which are carried at the ends of the webs ll, extending outwardlyfrom the walls 4 of the frame. Thus the cylinders 8 are adapted to be rotated in the vertical plane at the trunnions. The metal strip which is undergoing the stretching operation is indicated at I! and extends over the upper surface of the die 5, the latter being suitably rounded, as indicated, in It is apparent that when hydraulic pressure is applied to the cylinders 8, in a manner to be described hereinafter, and assuming that one of the rams 1 moves upwardly at a fasterrate than the other ram,

the cylinder which shows the greater ram movement will tend to rotate at the pivot l0 and move to a position. such as to cause the load to be dividedequally with the other ram. In order to maintain the cylinders in a normally vertical position, there may be interposed between each cylinder and the walls of the frame a compression spring, broadly indicated at l3, which is carried on a plate l4 bolted to the frame. Thus any movement of either cylinder from its normal vertical position would cause a compression of one .of the springs, depending on which side of the vertical position the cylinder is moved.

Construction of the clamping devices The strip l2, after passing over the platen 5, is gripped at each end or side by a clamping assembly, generally designated l5. Thisassembly is shown in section in Figures 8, 9 and and in plan in Figure 6. Each assembly takes the form of a rail-like member? indicated at 6, which preferably extends along the entire width of the machine so that the assembly can accommodate the maximum width of strip. The rail member I6 is provided with a large rectangular opening I! at the top, extending along the entire length of the rail member and is adapted to receive a plurality of clamping units. The latter are generally designated l8 and comprise supporting and clamping blocks constituted of tough metal such as nickel steel. As shown inFigure 6, the length of the rail member I6 is divided into a large number of these units I8, contained within each opening I1. The innermost surfaces of the supporting and clamping blocks are perfectly smooth, preferably ground, and when placed in position these surfaces are exactly parallel to one another and parallel to the strip contained between the surfaces. The blocks are held with in the opening ll at their outer upper edges by means of an overhanging ledge |9 (Figures 8 and 10), which fits into a corresponding groove in the blocks.

Each clamping unit is subdivided into two blocks, the outer one 20 of which is called the I supporting block and the inner one 2| is termed the clamping block. These blocks are spaced apart, as indicated at v22, by means of a pair of toggle levers 23. Each lever is constituted of a threaded rod 24 having a collar at the middle, the rod being received by cylindrically shaped metal elements 25. These elements fit snugly within cylindrical openings which extend longitudinally of the blocks 20, 2|. The rods 24 are ailixed'to the cylindrical elements 25 in such a manner as to cause the blocks 20 to be spaced from the opposite adjacent blocks 2|, as illustrated. The cylinders 25 and their openings preferably extend the entire width of each block.

Due to the togglearrangement provided by the cylindrical .members 25 and their interconnecting rods 24, each clamping block 2| is adapted to move upwardly, but in moving upwardlythe blocks 2| are constrained to move inwardly, i. e., away from the supporting blocks 20, due to the swivel action of the rod 24-cylinder 25 arrangement. In setting up and adjusting the blocks there is a space left between the inner surfaces of the inner pair of blocks 2| just enough snugly to receive the end of the metal strip l2 which is to be stretched. During the stretching operation the platen tends to pull the strip |2 out from between each adjacent pair of clamping units, and inasmuch as the clamping blocks 2| actually contact both sides of the strip, this movement of the strip will cause the blocks 2| to move upwardly on the ledges formed in the blocks 2|.

' pose of this will be explained presently.

and inwardly to increase their clamping eiiects on the strip.

The rectangular opening I! is provided with a countersunk rectangular groove 26 which leaves a ledge, indicated at 21, on which the two ,outermost sets of blocks 20 rest but provides aspace indicated at 28 directly below the inner sets of blocks 2|. The latter are maintained in their vertical position by resting on the upper ends of the round-headed pins 29, which are received in the vertical openings 30 drilled in the rail .middle, and then flares outwardly at the bottom,

as indicated at 33, to accommodate a, relatively large recessed opening 34. There are two rows of openings extending between the rectangular opening at the top of the rail member to the recessed opening 34 at the bottom of the rail member. These openings are positioned in line with the spaces 22 between the blocks 20, 2| on opposite sides of the strip I2. The openings 35 are positioned along the length of the rail member, one opening to each pair of blocks 20, 2|, and if the blocks are relatively long, then two or more openings per pair of blocks may be provided and symmetrically positioned with respect to each pair of blocks. These openings are adapted to receive bolts 36 of annular cross section, having bores 31 extending along the length of each bolt. Figure 6 shows only one bolt per pair of blocks, but it will be understood that as many bolts as may be necessary can be employed. Each bolt, 36 terminates at its upper end in a flanged head, indicated at 38, the upper portion of which is provided with a hexagonal opening 39 which is adapted to receive a socket wrench (not shown).

The opposite adjacent inner surfaces of each pair of blocks 20, 2| are provided with a round opening indicated at 40, which is adapted to receive the flanged head 38. This opening terminates at the bottom of the blocks 2| in a ledge 4|, on which the flanged head 38 of the bolt 36 rests. However, the opening 40 extends for a greater depth into the block 20 so that no ledge is formed at this point, and the bolt 36 rests solely The pur- The at their lower ends into a T-shaped bar 42, the horizontal portion. of which is carried within the opening 34. The rail member I6 is provided with a, longitudinally extendbolts 36 are threaded .ing slot, indicated at 43, which receives the upwardly extending portion of the bar 42. The bolts 36 are threaded into the bar 42 in such a manner as toleave a space 45 between the upper surface of the horizontal portion of the bar and the lower surface of the opening 34. A space 46 is also left between the upper surface of the metal portion 44 and the lower surface of the slot 43. A mechanism which will now be described is provided for moving the bar 42 in a. vertical direction in order to move the inner blocks 2| in a corresponding direction. This mechanism is generally indicated by the reference numeral 46', and is shown in detail in Fig ures 5, 6, 8 and 9.

The rail member I6 is provided at a number of positions along its length (three as illustrated) with transversely extending openings 41 having a necked portion 48 and adapted to receive a shaft 49. The shaft is round for the greater portion of its length, but at a position directly above the metal portion 44 is turned down, as indicated at 50, to conform to a cam shape. Consequently the shaft at this position has a portion which corresponds to the true diameter of the shaft, and another portion which is arcuate in shape formed by a radius greater than the radius of the shaft. The latter is provided with a tumeddown portion at one end which fits the smaller diameter part of the opening 41 and carries a washer secured to the shaft by a nut 52. Thus the shaft is prevented from moving in the longitudinal direction. At the opposite end the shaft is pinned to a hub 53 of a lever 54 which carries a connecting rod 55 secured to the levers 54 of the other two devices, as can be plainly seen in Figure 5.

One of the shafts 49, the left-hand one as shown in Figure 6, may be extended beyond the hub 53, as indicated at 56, and secured to a handoperated lever 51. By moving the lever 5'1 in a vertical direction the shafts 49 of the three devices are caused to rotate (due to the interconnecting bar 55), thus causing the cam surfaces 50 of the shafts to move either toward or away from the upper surface of the metal portion 44 (Figures 9 and 10), depending on the direction in which the lever 51 is moved. Directly below each cam surface 50 there is a wearing plate 58 of hardened metal secured by the screws 59 to a slot formed in the metal portion 44. Thus by rotating the lever 51 the T-shaped bar 42 can be rod 60 which extends through the central bore 31 of each bolt may be provided. This rod is pro-' vided at its upper end with a screw driver head 6|, to which access can be had through the hexagonal opening 39. The lower end of the rod is threaded into a bar 62 which spans the lower end surface of the bolt 36, and is pinned as indi cated at 63 to the bar 42. Thus by turning the rod 60 at the head 6| a locking action is effected which prevents any movement of the bolt 35.

Mechanism for moving the clamping assembly as a unit toward and away from the platen It is necessary to move the clamping unit assembly |5 (Figure 2) on each side of the platen 5 in a horizontal direction in order to accommodate different lengths of the strip l2 and in order to control the stretching operation, because as moved upwardly or downwardly within the rail member Hi, and if moved downwardly will cause the lower surface of the flanged portion 38 of the bolts 36 to exert a downward pressure on the ledges 4| of the inner blocks 2|, causing-these blocks to move downwardly against the action of the springs 3|.

Due to the toggle arrangement 24, 25, this downward movement of the inner blocks 2| causes these blocks to move away from one another, thus decreasing the pressure exerted against the strip l2. If the lever 5| is rotated through a sufficient angle, the inner blocks 2| will have moved outwardly to such an extent as to break all contact with the strip |2. Thus the latter can be readily removed from the jaws. It will be understood that there are as many of the clamp loosening devices 46' at one side of the rail member "5 .as may be necessary, depending on the length of the rail member, and it is further apparent that the rotation of the shafts 49 by the lever 51 causes the same outward movement of all of the individual blocks 2| on both sides of the strip l2, because the downward movement of the bar 42 exerts the same effect on all of the individual bolts 36 which rest on the ledges 4| of the individual blocks 2|.

During the operation of the stretching press it may be desirable to permit a certain amount of slippage at a particular point along the width of the metal strip, -but.to fully clamp other portions of the strip. In order to accommodate these different clamping and slipping effects it may be necessary to effect different adjustments at the bolts 36. It has been pointed out that as the bolts are tightened into the bar 42, the inner blocks tend to move away from one another, thus to permit any desired amount of slipp ge, and

the platen 6 moves upwardly, carrying with it the strip, the clamping units must move inwardly with a corresponding or predetermined rate of travel. Each clamping assembly is carried on a fiat plate 64 which rests on the plate I of the press, and which is reenforced by a number of diagonally extending ribs 65, connecting the plate 64 with the outer surfaces of the rail member ii. The plate I has a large rectangular shaped opening 66 extending inwardly from each end of the plate. As will be explained in connection with other operating mechanism, the width of this opening is suflicient to clear a sprocket mechanism which is generally designated 61. Secured to the bottom surface of the plate 64 there is a pair of spaced downwardly extending box-shaped members 68 (Figures 3 and 5). A nut 69 is contained within each box member, and there is a rod 10 which passes through openings in the. sides of the box and is threaded in the nut. The

latter preferably has a cylindrical shape for purposes which will appear hereinafter, the axis of the-cylinder being vertical (as seen in Figure 3) so that the. rod 10 extends through the diameter of the cylinder. The purpose of this rod will be explained hereinafter. The rod 10 has a shouldered portion indicated at H where it passes. through the inner wall of the box 58, and is secured to the box by' a nut 12.

There is a web of metal 13 secured to the under side of the box-shaped member 68 and is therefore secured to the plate 64, this web being provided with a right-angle extension, indicated at 14 and which has a bore 15. The web 13 is provided with outwardly extending ledges 16 at each side (Figure 5), these ledges being adapted to ride in grooves formed at opposite sides of a box-shaped member 4 forming part of the frame. A ram 11 passes through the bore 15 and is secured to the web I3 by a nut 18. This ram is received in a hydraulically operated cylinder 13 at one end, and at the other end is supported by a bracket lug which is securedto the frame. It will be understood that there are two sets of cylinders 19 for each Jaw unit l5 and consequently two box-shaped members 4, and two sets of the apparatus contained in thebox-shaped members. These cylinders are obviously positioned in a horizontal plane, and are preferably arranged at the same height so that one of the pairs of cylinders for one Jaw body is placed end to end with the corresponding cylinder of the other jaw body I5. When fluid pressure is applied to the pistons contained in the cylinders 19, the clamping unit assemblies I will be given a movement either inwardly toward the platen or outwardly away from the platen, depending on which side of the-piston receives the pressure fluid.

It has been pointed out that in order to stretch strips of metal into certain shapes, the assemblies I5 may have to be canted in the horizontal plane, i. e., move the corresponding ends of the clamping units either toward or away from one another so that these units will not extend in parallel directions but instead be positioned at an acute or obtuse angle withrespect to one another. In order to obtain this adjustment there are two rods 10 provided for each assembly I5. these rods being threaded in the nuts 69 which form part of the moving carriage on which the clamping units I5 are mounted. Th rod 10 at the opposite end is provided with an axially extending bore 8| which receives a case hardened shaft 82. The latter is keyed to the rod 10, as

indicated at 83 (Figure 4), and is journalled at' the outer end in a bearing 94 which is supported on a verticalextension of the frame member 2. The shaft 82 extends beyond the bearing 88 and carries a sprocket wheel 95.

At the center of the machine the frame 2 is provided with a horizontal platform 99, on which is mounted a pair of spaced uprights 91. The latter are provided with round openings in which is swivelly mounted a U-shaped member 89 having hubs 89 and 90 which are adapted to rock within the openings in the uprights 81. The U-shaped member merges at the top into a flat bar portion 9|, which in turn spreads out into a U-shaped member 92 (Figure ll). The hub 89 is bored to receive a sleeve 93, the latter having an opening which contains a. shaft 94. The sleeve is adapted to rotate on the shaft and carries at itsleft-hand end a sprocket 95 secured thereto by a.pin 98.. At its opposite end the sleeve 93 carries a sprocket 91 which is secured thereto by the pin 98. A sprocket 99 is fixedly mounted on the shaft 9| by means of a pin I00, and at its left-hand end the shaft carries a sprocket IOI to which it is secured by means of a pin I02.

Referring now to' the upper end of the bar 9i, the U-shaped element 92 is provided with a hub member I03 which is adapted to rotate within a cap element I 04 forming the central. hub of the hand wheel I05. The Ll-shaped element 92, together with its hub member I09, serves as a bearing for a shaft I06. The latteris provided at a position in lin with the bar 9| with a key I01, and at its right-hand end is pinned, as indicated at I08, to the cap-shaped member I04 of the hand wheel. Thus by turning the wheel I05, the shaft I06 can be rotated. Within the legs of the U-shaped member 92 there is positioned a pair of sprockets I09, I I0, the inner faces of which abut one another and the outer faces are held in position by the legs of the member 92. These sprockets are mounted on the shaft I06 and are provided with registering keyways III, I I2 at the position of the key101, the length of each keyway III, II! being equal to that of the key I01 so that the total length of the keyways III, H2 is approximately twice that of the key as indicated.

The hub member I03 is provided with a countersunk opening 9, and about midway the length of the opening there is provided a shoulder Ill on the shaft I06. Compression springs II5 are positioned in the compartments thus formed on opposite sides of the shoulder, the springs being retained in place by the right- .hand surface of the sprocket H0 and the flat surface of .the opening 9. A sprocket chain H5 is connected between the sprocket wheels I09 and 91, and a similar chain is connected between the sprocket wheels IIO and 99. A chain H1 is connected between the sprocket wheel IOI and the sprocket wheel 95 (Figure 5), and a chain I I8 is connected between the sprocket wheel 95 and a sprocket wheel II9 which is carried on the end of the other rod 10, as can best be seen in Figure 6.

Assuming that the hand wheel I05 has been neither moved inwardly or outwardly but is in the position shown in Figure 11,.so that the key I01 contacts both keyways III, H2 in the sprocket wheels I09, IIO; any movement of-the wheel in either direction will rotate both sprockets I 09, H0, causing asimilar rotation of the sprockets 91 and 99. Rotation of sprocket 91 will rotate the sprocket 95, and the rotation of sprocket99 will cause rotation of the sprocket Let us now assume that the hand wheel is pressed to the left against the left-hand spring 9 I5, and causing the key I01 entirely toleave the keyway H2 and completely to engage the keyway III. If the wheel I05 is turned under these conditions only the sprocket I09 will be rotated and the sprocket 01 so that the sprocket II9 will be turned. The opposite sprocket 85 will remain stationary. A rotation of the right-hand rod 10, as seen in Figure 6, will cause the carriage to swing around the circular nut 69 of the other rod as a pivot so that the carriage and the clamping assembly mounted thereon will now be canted with respect to the opposite carriage and its assembly. The clamping assemblies may be caused to extend at an acute or an obtuse angle with respectto one another, depending on the direction in which the wheel I05 is turned.

On the other hand, if the hand wheel I05 were to be pulled outwardly, i. e., to the right as seen in Figure 11, so as to. compress the other spring II5, the key I01 will entirely leave the keyway sprocket I I0; and through the sprockets IM and will cause the left-hand rod 10,'as seen in Figure 6, to rotate. Under these circumstances the carriage on which the clamping assembly is mounted will now pivot about the cylindrical nut 69 of the opposite rod 10, and in a direction depending on the direction oi rotation of the wheel I05. Thus the left-hand end of the assembly is moved in a horizontal direction with respect to the right-hand end in order again to provide a cant between the line of clamping units.

As shown in Figure 2, there is a hand wheel I and its associated apparatus at each side of the machine in order to cant either one or both of the jaw assemblies I5 in any horizontal direction, or to move either or both of the assemblies along parallel paths either toward or away from the platen 6. The operation performed by the hand wheels is usually of a preliminary nature and represents an .adjustment which is determined by the size and shape of the strip to be stretched, also by the configuration into which the strip is to be stretched. In order to remove the slightest possibility of the adjusting mechanism obstructing the view of the operator during the stretching process, the bar and its hand wheel and'sprocket mechanism can be swung at the hubs 83, 90 from its vertical to its horizontal position or beyond, and if necessary a well or other depression may be provided in the floor to receive the hand wheel and its associated apparatus. There is ordinarily no need to reinstate the bar 9| in its vertical position until either changes in the size of the strip or in the shape of the piece to be formed shall be required.

Auxiliary main cylinder apparatus In certain lengths or widths ofstrip material, or in the case of certain shapes into which the strip is to be formed, it may .be necessary to arrange the platen lengthwise of the machine. It will-be noted that in Figures 2, 3 and 5 the platen has been shown transverse of the machine. As shown in Figure 7, an extra pair of main cylinders I (of which only one cylinder is shown in this figure) may be provided, this line of cylinders being displaced from the other line of main cylinders ninety degrees. As in the case of the other main cylinders 8, rams I2I may be provided which terminate in hemispherical heads I22. These heads fit in spherical openings formed at the ends of the platen I23. It will be noted that the upper surface of theplatencontacts the strip I throughout a much greater distance than the platen 6 in the case of the transversely positioned main cylinders. Thus the punch I24 produces an object of considerably different shape from that formed by the punch 5. Another point of difference between the two types of punches is that in the case of the punch 5 contact with the strip I2 is made at the start of the pressing Qperation onIy at the uppermost surtlon. Thus any stresses set up in the cylinders or in the rams during the stretching operation, caused by unequal. pressure in the cylinders or by the difference in travel of the respective rams. are equalized. The cylinders are maintained in a normal vertical position by means of springs I21, which are maintained at the proper height by means of countersunk plates I28 secured to the frame, and which receive the springs. A similar arrangement is employed in connection with the transversely positioned main cylinders.

One point of diiference between the two sets of main cylinders is that the cylinders 8 are positioned so close to the ends of the carriage on which the clamping assembly is mounted as to prevent rotation on the trunnions I0 except for the amount of-rotation necessary to relieve the cylinders of unequal stress. On the other hand, the auxiliary cylinders I20 are positioned relatively far removed from the carriage so that when these cylinders are not in operation they may be rotated the fullninety degrees to get them out of the way, and prevent any obstruction to the operators view. In order to assure full clearance for the vertical movement of the auxiliary cylinders, the plate 64 on which the clamping assembly is mounted may be provided now be explained.

I Hydraulic c'z'rcait The hydraulic system is shown in Figure l.

' The fluid pressure for actuating the cylinders 8 and the auxiliary cylinder I20 is obtained from face of the punchfallowing a complete stretchiiig movement of themetal strip between this surface and each clamping unit until the platen has reached its uppermost position, at which time full contact over the entire surface of the punch is made. The feature of preventing full contact between the punch and the strip during the initial stretching operation is enhanced by the fact that the assemblies I5 are spread wide apart at the start of the stretching operation,

thus causing the strip to leave the punch at a tangent. Obviously, the closer to 'a straight line:

tank I.

the main pump I30. The high pressure side of the pump is taken through a conduit I 3|, into a valve I32 which iscontrolled by a hand-operated lever I33. A conduit I34 is taken from the valve I32, into a valve I35 which is controllable by a hand-operated lever I36. From the valve I35 a conduit I31 passes into one Of the cylinders 8,

another conduit I38 passing from the valve I35 to the auxiliary cy1inderl20. A conduit I39 is taken from the valve I32, through a conduit I40 to the tank I. The low pressure side of the pump I30 is connectedto the tank through the conduitI42. A similar: set of hydraulic connections and valve is provided for the other of the main cylinders 8 and for the other of the auxlliary cylinders I20, and will be given similar reference numerals. A conduit I43 is taken from the tank I to a four-way valve I44 of suitable and well known type, and controlled by a lever I44, which has forward, neutral and reverse positions. Two conduits I45, I40 extend from this valve and connect respectively with conduits I41, I40 which lead to the opposite sides of the pistons contained in the cylinders I9. The valve I44 is provided with high pressure fluid through a conduit I40 by the pump I 50, th low pressure side of which is connected by a-conduit I 5I to the The hydraulic system for one pair of cylinders I3 is the same as for the other pair so that both systems will be designated by the same reference characters.

Assuming that the pumps I30 and I are actuated, for example, by meansof an electric motor, and the'valves I32 have been adjusted to admit pressure fluid to the cylinders 8, thus causing the platen 5 to rise. As the platen continues to ascend it may be necessary to move the clamping assemblies I5 inwardly in order to allow a predetermined amount of upward movement of the will metal strip I2. The operator would then move the valve I by the lever I44 into the forward position, which would cause pressure fluid tobe admitted to the conduits I46v and therefore to the outside surfaces of the pistons contained within each pair of cylinders I9. The movement moved inwardly at arate depending on the rate at which pressure fluid is admitted to the opposite sides oi the pistons.' A skilled workman can, after little experience, determine how last to admit pressure fluid to the conduits I46 in order to regulate the inward movements of the clamping assemblies, At the same time the operator will control the levers I33 to regulate the rate of admission of pressure fluid to the main cylinders 8;

If during the stretching operation it is destretching cylinder shut also control the rate at which the clamping assemblies are caused to sired to maintain the clamping assemblies rigid.

at a particular position, i. e., so that they. no longer. move' inwardly, the. operator will move the lever Ill of the valve I to its neutral position, which in the case of a four-way valve prevents the admission of high pressure fluid to the conduits I45 and also prevents the exhausting of fluid'through the conduits I45. Thus the pistons in the cylinders I5 are'malntained rigid in their last position.

After the stretching operation the strip in its formed shape is removed from the clamping units 25, 2| by rotating the levers 51 (Figure 6), which as pointed-out hereinbefore, serves to .move the blocks 2| outwardly away from the strip. The clamping assembly 20,21 can then be returned to its initial position, ready for the insertion of a fresh metal strip, by moving the lever "'4' to its reverse position, at which time high pressure fluid is admitted to the conduits I45, causing the pistons within the cylinders I8 to be moved outwardly and car ying the assemblies with them. In'case it is desired to stretch the metal stripby turning the platen 6 ninety degrees from the position shown in Figure 1, and thus to actuate the cylinders I20, the latter are rotated from their normal horizontal position to a vertical position in any suitable manner, and when placed in position under the platen the valves I35 are moved to cause high pressure fluid to enter the conduits I38. Control of this pres- I sure fluid can be maintained at the valve I32 in the same manner as the control of the pressure fluid admitted to the main cylinders I.

From the foregoing it is evident that there is disclosed a stretching press having the greatest move toward or away from the-platen, or if desired maintained in a rigid position with respect to the platen. There is also provided a convenient means iorreleasing the strip from the blocks by simply moving a pair of levers 51. It will be noted thatpressure fluid is admitted separately to the cylinders 8, this fluid being under the control of the individual valves I32. Consequently, on'e end-oi the punch or die .5 may, if desired, be moved at a faster rate than the-other end' in case it is necessary to form articles of complicated shape. The fact that the opposite ends of the platen 6 may be raised at different speeds isillustrated in Figure -2 by showing the front, edge adjustments of eachset oi. blocks-20, 2| at the adjusting bolt 36. Auxiliary stretching cylinders- I 20 are provided toextend the usefulness of the press in accommodating those formed articles which may be pressed to shape only by arranging the platen at ninetydegrees from its usual position. Unequal stresses throughout the stretching cylinders are also relieved by the provision of mounting these cylinders 0n trunnions. Finally, all of the apparatus which serves to preliminaril'y adjust .the jaws may be swung away from the press so as to give the operator a clear view-of the work'during the stretching operation. It will be understood that I desire to comprehend within this invention such -modifications as come within the scope of the'claims and the invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a stretching press, a pair of spaced clamp- .ing devices for gripping a metal strip to be stretched, a. platen positioned between said detween said devices, at least'orie of said'devices universality of use in that provision is made for permitting any amount of slippage or full clamp- 'ing eflects at the clamping assemblies'by individually adjusting the blocks II at the bolts 55..

The refinement to which the slippage efiects can be carried is determined solely by the number of individually adjustable blocks into.whi'ch each assembly is divided. As another preliminary ad-* justment, there is also a means provided for canting one or both lines of clamping units in any horizontal plane to accommodate the complex shape into which themetal strip may be stretched. The clamping units as a whole may also be moved parallel to one another.

The hydrauliccircuit shown in Figure 1 is so arranged 'thatthe operator may not only control the admission of pressure fluid to the main vices, and means for moving the devices toward and away from the platen as the stretching op-' eration proceeds, and means comprising a pair or actuating members plvotally secured at spaced points to each clamping device, and" a single means fordriving said actuating members including means for driving'them at will in the same or in opposite directions. 1

2. In a stretching press, a plurality of spaced clamping devices for gripping a metal strip to be pressed, a stretching platen positioned bebeing adapted tobe moved in aplane at right angles to the direction or movement of the stretching platen, and means comprising a pair of actuating members points to each clamping device, and a single means for driving said J actuating members in-' cluding means for, driving them at .will in' the same or in opposite directions.

3. In a stretching press, a plurality of spaced clamping assemblies to be stretched, a stretching platen positioned between the assemblies, at leastone of said assemblies being swivelly mounted on the press and at least one of said assemblies being adapted to be moved toward and away from the platen, and means external oi. the press for giving the assemblies any desired angle with respect to one another and for moving the assemblies toward and away from one another, and means comprispivotally secured at spaced .ior gripping a metal strip ing a pair of actuating members pivotally secured at spaced points to each clamping device, and a single means for driving said actuating members .including means for driving them at will in the same or in opposite directions, or selectively to drive either actuating member in one or the other direction while the other actuating member remains stationary.

4. In a stretching press, a pair of spaced clamping devices for gripping a metal strip to be stretched, a stretching platen positioned between the devices and adapted to move in a vertical direction, both of said devices being mounted for movement in a horizontal direction about ing means comprising a pair of actuating members pivotally secured at spaced points to each clamping device, said hand wheel being connected to said last named means whereby said devices may be moved at will by means of said hand wheel in the same, or in opposite directions.

5. In a stretching press, a plurality of spaced sired angle with respect to one another and for v moving the devices toward and away from one another, a rod for actuating the swivel of the swivelly mounted device, and a hand wheel on a vertical support for operating said rod, said hand wheel being adapted to be swung out of the vertical to an approximate horizontal position in order to remove the hand wheel and its support from the operators view.

6. In a stretching press,'a pair of spaced clamping devices for gripping a metal strip to be stretched, a stretching platen positioned between the devices, said devices being mounted on pivot, rods which extend in a direction parallel to the axis of the platen, said pivot rods being adapted to be moved toward and away from one another, whereby the-devices may take positions which represent the composite movement of the rotation or the devices about their pivot'rods andthe movement of the pivot rods with respect to one another, and means comprising a pair of actuating members pivotaliy secured at spaced points to each clamping device, and a single means for driving said actuatingmembers including means 60 for driving them at will in the same or in opposite directions, or selectively to drive either actuating member in one or. the other direction while the other actuating member remains stationary.

7. In a stretching press, a plurality oI-spaced clamping devices for gripping a metal strip to be stretched, a stretching platen positioned between the devices, at least one of said devices being swivelly mounted on the press for canting the device with respect to the platen, each portion of said device also being adapted to be moved throughout equal distances toward and away from the platen, and a common means for changing the angle that the device makes with the platen and ior moving the devices with respect to the platen, said means including rods which are secured to opposite ends oi! the device, and meansincluding a common actuator for moving the rods through unequal distances and in differ ent directions in order to cant the device, said actuator also being adapted to move the rods through the same distances and in the same direction. a 8. In a stretching press, a plurality of spaced clamping devices for gri'pping a metal strip to be stretched, a stretching platen positioned between the devices, at least one of said devices being swivelly mounted on the press for canting the jaw with-respect to the platen, said device also being adapted to be moved throughout equal distances over its entire lengthtoward and away from the platen, a common means for changing the angle that the device makes with the platen and for moving the device with respect to the platen, said means including rods which are secured to opposite ends oi, the jaw, and meansior.

moving the rods through unequal distances and in difierent directions in order to cant the device,

said last-mentioned means also including mechanism by which the rods are moved the same distances and in the same direction, the mechanism for canting the device andfor moving'the same bodily with respect to the platen being constituted of a sprocket chain transmission and a hand wheel for actuating the transmission, separate connections from said transmission to said rods to effect their movement in opposite directions, or in the same direction, at will, said hand wheel being mounted on a shaft and adapted to be moved in a direction along the shaft, the

said common means further including means whereby when the hand wheel is-moved to its innermost position one portion of the sprocket chain transmission is operated to move one of said rods, and further including means whereby when the wheel is at its other extreme position the other of said rods is'moved to effect a different cantat the device, and further including means whereby when the hand wheel is in a P sition intermediate its two extreme positions both of said rods are moved equally in order to move the device throughout equal distances and over its length toward and away from the platen.

.9. In a stretching press, a stretching platen,

59 and means including rams positioned at opposite ends of the platen for moving the platen in a vertical direction during the stretching operation, said rams being contained in cylinders which are pivotally mounted on horizontal axes, said pivotal mountings being located in positions to provide for movement of said cylinders from their ver-' tical stretching positions 90 to horizontal inoperative positions in order to prevent obstruction of the operator's view.

10. In a stretching press, the combination of av pair of longitudinally extending clamping devices, a platen positioned between said devices, hydraulic means for moving both ends of the devices with respect to the platen and through equal distances, and hand-operated means and connections from said means to said clamping devices constructed and arranged for controlling the movement of and aligning the clamping devices at an angle with respect to one another.

11. In astretchingpress, the combination of a pair of longitudinallyextending clamping devices, a platen positioned between the devices, separate hydraulically operated means for mov- .ing the devices independently of one another toward and away from the platen, a pair of ram disposed at opposite ends of the platen, and hydraulic means for operating said rams independently of one another to cause them to move in directions at right angles to the directions of movement of said devices whereby the position of each device with respect to the platen and the position of each of said rams with-respect to the devices can be independently controlled.

12. In combination, a clamping device comprising a rail member having a groove along the length of the rail and containing an inner and an outer set of blocks, each set comprising two rows of blocks, said inner rows of blocks being adapted to receive a strip of metal, the outer set of blocks being in contact at the side and bottom with said groove, yielding means for holding the inner row of blocks from the bottom of the groove, the inner and outer sets of blocks being secured together by toggle mechanism, and means including bolts passing between the inner and outer sets of blocks said bolts having projecting portions in engagement with said inner blocks and said bolts being secured to a rigid bar for causing the inner set of blocks to be simultaneously moved toward the bottom of the groove so inner row of blocks from the bottom of the groove, the inner and outer sets of blocks being secured together by toggle mechanism, and means including bolts passing. between the inner and outer sets of blocks and secured to a rigid bar for causing the inner set of blocks to be simultaneously moved toward the bottom of the groove so as to causeseparation of the blocks of the inner set from one another and thus to open the clamping device, said last-mentioned means also including at least two rods, the corresponding ends of which are adapted to rotate in said bar and the other ends are extended to the exterior of said device, and common means for rotating said rods simultaneously, said rods having cam surfaces which are adapted to bear against wearing plates whereby upon rotation of the rods by the common means the cam surfaces cause the bar to be moved each pair being selectively adapted to engage a said bar to thereby cause movement of the inner .35

set of blocks with respect to eachother and to open said clamping device. i

13. In a stretching press, a plurality of spaced clamping devices for gripping a metal strip to be stretched, a stretching platen positioned between the clamping devices, at least one of said devices being swivelly mounted on the press and at least one of said devices being adapted to be moved toward and away from the platen, and means external of the press for giving the clamping devices any desired angle with respect to one another and for moving the devices toward and away from one another, said means comprising a pair of round-headed swivels positioned along one clamping device and rods threaded into said swivels, said rods extending to a position external of the press, separate sets of sprocket and chain connections and a single manually operable mem ber therefor for operating said rods simultaneously, and means to render inoperative at will either of said sets of connections while the other set of connections remains in operation in order to cause the clamping devices to rotate around either of said swivels.

14. In combination, a clamping device comprising a rail member having a groove along the length of the rail and containing an inner and an outer set of'blocks, each 'set comprising two rows of blocks said inner rows of blocks being adapted to receive a strip of metal, the outer set of blocks being in contact at the side and bottom with said groove, yielding means for holding the common stretching platen, all of said ram pairs being mounted on horizontal pivots and at least one of said ram pairs being adapted to be swung from the vertical to the horizontal position.

16. A metal stretching press which includes a clamping device for gripping a metal sheet, a press platen, a carriage and fluid operable motor means including a reciprocable member for varying the position of said clamping device relative to the press platen, said clamping device being pivotally connected to said carriage, said carriage being movable on the press and rigidly connected to said reciprocable member.

17. A metal stretching press with a press platen, a metal sheet clamping device movable relative to the press platen, a fluid operable motor, 1

18. A metal stretching press with a press platen, a metal sheet clamping device movable relative to the press platen, a fluid operable motor, a

carriage, said motor having a reciprocable member rigidly connected with the carriage, said carriage being movable on the press and carrying two spaced pivots associated with the clamping device, each of said pivots constituting a single point of rotation about which the opposite end of its respective clamping device is adapted to move, each of said pivots being formed as a nut which is threadedly engaged by an adjusting screw.

19. A press according to claim 18 in which the adjusting screws are drivingly connected with a driving element common-to said screws and operable selectively to actuate only one of said screws and both of said screws simultaneously.-

PAUL E. FLOWERS. 

